Automatically movable irrigation systems have been employed for a considerable period of time for the purpose of irrigating land areas under conditions where rainfall is insufficient for optimum growing of crops. One example of a tower suppoted movable irrigation system which, in this case, is movable in circular manner about a central water supply pivot is depicted in U.S. Pat. No. 3,808,823 to Reinke. Where movable wheel tower supported irrigation systems are employed, in some cases the speed of rotation or speed of movement of each of the sections of irrigation pipe is controlled by a single speed electric motor that is intermittently energized and deenergized responsive to the angular relationship between the particular pipe sections that are involved. The electric drive motor, together with its reduction gear mechanism, will remain deenergized until a particular horizontal angular relationship is reached responsive to movement of adjacent towers of the irrigation system at which time the electric drive motor will become energized thus moving its associated tower sufficiently to develop another predetermined horizontal angular relationship between the pipe sections involved, at which time the motor will be deenergized. This feature eliminates the need for expensive motor drive systems of varying speed for each of the pipe sections that revolve about the central pivot point and enhances the competitive nature of such irrigation systems.
As tower supported irrigation systems move during irrigation of land areas, changes in grade occur due to unevenness of the land surface. It is necessary that the various pipe sections that interfit to transport water from the water supply to the irrigation system be capable of vertical movement to accomodate changes in grade as well as accommodating horizontal angular misalignment responsive to tower movement. It is therefore desirable to provide coupled irrigation pipes with a pipe coupling that efficiently allows universal movement of the connected pipe sections so as to prevent the development of any strains that might otherwise cause deterioration of the connections between the pipe sections.
Where irrigation pipes are supported by mobile towers, it is typical for each extremity of each of the various spans of irrigation pipe to be physically supported by the mobile tower devices or by load supporting devices that are in turn supported by the mobile towers. The irrigation pipe sections defined by the various spans of the irrigation system must be supported in such manner that the extremities of adjacent pipe sections will be positively aligned. Such support structures for the pipe sections are typically quite expensive and serve to detract from the commercial feasibility of the irrigation system.
The above noted patent to Reinke illustrates utilization of a particular universal coupling, typically known as the "hook and eye" coupling which is disposed internally of the pipe sections and provides for the amount of universal movement that is desirable. The desirability of the Reinke coupling structure, however, is considerably reduced by interference of the hook and eye connection structure to free flow of water through the iterconnected pipe sections because the coupling presents an obstruction in the flow path of the pipe sections.
As tower supported irrigation systems move about land areas during irrigation operations, it is known that severe tensile and compressive forces are exerted on coupled pipe sections, thereby requiring that the pipe couplings be quite heavy and strong to prevent the couplings from being pulled apart. Obviously an internal "hook and eye" type pipe coupling such as identified in the patent to Reinke, if manufactured of sufficient size to effectively withstand the tensile and compressive loads that are applied thereto, will be of sufficient size to also cause severe restriction of the amount of water flow that can be accomplished at a given water supply pressure. It is necessary when utilizing internal pipe connections of this nature to deliver irrigation water at a higher supply pressure than would be necessary if the irrigation pipe were substantialy free of obstructions. This causes pumping and power requirements to be greater than would be necessary if unobstructed irrigation pipe were employed and thereby adds unnecessarily to the cost of supplying irrigation water to land areas.
It is therefore a primary object of the present invention to provide a novel universal coupling for irrigation pipes that effectively allows both horizontal and vertical misalignment of connected pipe sections without developing excessive strain on the pipe coupling that might otherwise result in damage to the irrigation pipe system.
It is another important feature of the present invention to provide a novel universal coupling between pipe sections of an irrigation system, wherein the mechanism for restraining tensile loads applied to the pipe sections is easily capable of withstanding such tensile loads.
It is another feature of the present invention to provide a novel universal coupling for irrigation pipes that presents a substantially unobstructed flow passage for the water being supplied, allowing the capability of the water supply pumping system to be minimized for a given volume of water that is supplied.
Another feature of the present invention contemplates the provision of a universal pipe coupling, wherein the extremities of pipe sections to be connected are of a size and configuration to allow one extremity of one pipe section to be received within an extremity of the adjacent pipe section in a load bearing supporting/supported relationship.
Among the several features of the present invention is contemplated the provision of a novel universal coupling for irrigation pipe systems, wherein one or both of the extremities of pipe sections to be coupled are of a configuration allowing relative vertical movement of the pipe sections during assembly or disassembly operations.
It is also an impotant feature of the present invention to provide a novel universal coupling for irrigation pipe systems wherein the weight of the irrigation pipe, the truss assembly for the irrigation pipe and the water within the irrigation pipe are employed to maintain adjacent sections of irrigation pipe in assembly.
It is also a feature of the present invention to provide a novel universal coupling for irrigation pipes, wherein a bearing and positioning element is employed that may be disposed between the connected pipe sections and which achieves proper vertical alignment of the adjacent pipe sections as well as preventing wear that might otherwise occur during transverse pivoting of the pipe sections at the coupling.
Another feature of the present invention contemplates the provision of means for establishing a fluid tight seal about the pipe coupling assembly, which means may conveniently take the form of an external sealing boot disposed in sealed relation about the coupling.
It is another feature of the present invention to provide a novel pipe coupling structure for irrigation pipes wherein the coupling structure efficiently restricts the amount of relative rotation that can occur between adjacent pipe sections.
Other and further objects, advantages and features of the present invention will become apparent to one skilled in the art upon consideration of this entire disclosure. The form of the invention, which will now be described in detail, illustrates the general principles of the invention, but it is to be understood that this detailed description is not to be taken as limiting the scope of the present invention.